Technically, it's a process called explosive cyclogenesis, or bombogenesis, when a weather system drops at least 24 millibars over 24 hours. Meteorologists use millibars to measure atmospheric pressure, and-as pressure drops storms get stronger.

Winds from this storm have already been clocked at nearly 80 mph, equal to a Category 1 hurricane. More than 70 million people are at risk for severe weather, with half of the United States under severe watches or warnings.

Blizzard conditions are developing on the western side of the storm, with up to a foot of snow and very strong winds reported.

This storm will weaken as it moves towards Pittsburgh Thursday, bringing the threat for rain, a possible thunderstorm, and wind gusts of 40 mph.